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New perspectives in nutrition management of diabetes mellitus
New Perspectives in Nutrition Diabetes Mellitus JAMES W.
ANDERSON, M.D., PATTI BAZEL GEIL,MS.,
R.D.
fexington,
Management
of
Kentucky
iabetes mellitus is a complex metabolic disorder D affecting metabolism of carbohydrates, fats, and other nutrients. Appropriate nutrition management is
Diet remains the cornerstone in the management of diabetes mellitus. A prudent nutrition plan reduces the exaggerated risk for atherosclerotic heart disease and metabolic complications of diabetes by improving lipid and glycemic control. The current consensus diabetes diet recommends 55 to 60 percent of energy as carbohydrate, 12 to 20 percent as protein, and less than 30 percent fat. Total cholesterol intake should be less than 300 mg per day. Fiber appears to have distinct benefits in improving glucose and lipid levels; therefore, an intake of up to 40 g per day or 15 to 25 g/1,000 kcal of food is recommended. Other considerations in meal planning for diabetes include alternative sweeteners, salt intake, alcohol consumption, and vitamin and mineral needs. Individualized and flexible nutrition plans, designed within established guidelines, promote adherence. Persons with diabetes can change their eating patterns and closely adhere to a diet plan if the entire health care team is enthusiastic, supportive, and instructive.
essential for restoring and maintaining a normal metabolic state. In addition to reducing the risk for the metabolic complications of diabetes, a prudent diet also reduces risk for atherosclerotic cardiovascular disease. Diabetic persons are at distinctly higher risk for coronary heart disease and cerebrovascular disease and at substantially higher risk for peripheral vascular disease than nondiabetic persons. A prudent diet favorably affects, reduces, or reverses these risk factors for atherosclerotic vascular disease: hypercholesterolemia, hypertension, hypertriglyceridemia, obesity, abnormally sticky platelets, hyperinsulinemia, and hyperglycemia. The last decade introduced several new considerations to the nutrition management of diabetes. In the carbohydrate arena, we have dietary fiber, an endorsement of a generous complex carbohydrate intake, new insights into the glycemic effects of simple and complex carbohydrate, and new artificial sweeteners. Relative to fats as a nutrient., available are fish oils and fat substitutes, and there 1s a new appreciation of monosaturated fats. We now have to consider the role that the amount and type of protein may have in the risk for renal disease. Thus, diet remains the cornerstone in the management of diabetes as it has for over two millennia. Intelligent adherence to a suitable nutrition plan not only reduces risk for metabolic complications by enhanced glycemic control, but also reduces risk for atherosclerotic cardiovascular disease, the major risk for decreased quality of life and premature death.
GOALS Recommendations for nutrition management of diabetes mellitus should be based on achieving one underlying aim-a healthy patient with a full lifestyle and normal longevity. Specific as well as general goals aid in accomplishing this aim. Fundamentally, the primary purpose of nutrition therapy is to achieve normal or physiologic blood glucose levels by optimizing glucose use, normalizing glucose production, and enhancing insulin sensitivity. Persons with diabetes die from coronary vessel disease two to three times more frequently than do nondiabetic persons. Since average serum lipid levels are higher in diabetic than non-diabetic persons? maintaining desirable plasma lipid levels is a specific goal that may retard the development of atherosclerosis I
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From the Department of Endocrinology and Metabolism, Veterans Administration Medical Center, and the Uwersity of Kentucky, Lexington, Kentucky. Requests for reprints should be addressed to Dr. James W. Anderson, Veterans AdminIstration Medical Center, Medical Services IIIC, Cooper Drive, Lexington, Kentucky 40511. I
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Another long-term objective of nutrition therapy is to reduce the frequency of specific diabetic complications such as retinopathy, nephropathy, and neuropathy. Although the origin of these complications is not 28, 1988
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exogenous insulin requirements, an increase in life expectancy, and improved health [3]. Any person following a weight-loss program should be closely supervised by health professionals. Ideally, such a program would be nutritionally balanced with a calorie reduction of 500 to 1,000 kcal below normal daily levels. The key to sustaining successful weight loss is a long-term behavioral approach in follow-up. In some cases, a more marked caloric reduction may be needed to produce a more rapid weight loss. Very low-calorie diets have been studied in a small number of persons with type II diabetes with reportedly safe and effective results in the short term [4]. Concern remains about the long-term use of very low-calorie diets, particularly in the area of endogenous protein metabolism.
gure 1. Influence of nutrition on major risk factors contributing to atheroscleros diabetes.
fully understood, it seems logical that good management will reduce the risk for metabolic, macrovascular, and microvascular complications. These specific goals are founded on general nutrition recommendations for overall health and wellbeing. The diabetes diet must provide appropriate amounts and varieties of nutrients. It should assist the person with diabetes in attaining and maintaining desirable body weight while meeting energy needs in a timely manner. Flexibility within specific recommendations, particularly in the area of food preferences and availability, will promote adherence to the nutrition plan. Unique physiologic requirements and therapeutic modifications for medical conditions should be considered as general goals for nutrition management of diabetes mellitus.
Carbohydrate Recommendations for the amount of carbohydrate to provide in the diabetic diet have sparked controversy as far back as the 16th century B.C., when Egyptians prescribed diets with high levels of carbohydrate to combat the dissolving of flesh into the urine. Since that time, medical science has suggested that the consumption of carbohydrate be severely restricted. This viewpoint became liberalized over time to the point that in 1988 we recommend the carbohydrate content of the diet be 55 to 60 percent of total calories consumed. Diets high in complex carbohydrate and fiber improve glycemic control and lower serum cholesterol concentrations. Although concentrated carbohydrate may worsen glycemic control [5] and promote weight gain, the 1985 American Diabetes Association Task Force on Nutrition suggested that “modest amounts of sucrose and other refined sugars may be acceptable, contingent on metabolic control and body weight.”
Due to new and emerging information regarding the effects of diet on blood glucose concentration, the role of nutrition in the management of diabetes mellitus continues to be examined. In 1985, the American Diabetes Association appointed the Task Force on Nutrition to update guidelines and formulate new recommendations for diet therapy. The findings of the Task Force were summarized and published [21. However, new facts in the field are evolving rapidly and continued updates and revisions are required. The following is a summary of current knowledge in key areas.
Protein The primary function of protein in the diet is for growth and tissue maintenance. Although the nutritional recommendation for protein in the diabetes diet is 12 to 20 percent of calories, this amount exceeds the adult Recommended Dietary Allowance of 0.8 g/kg body weight. The Recommended Dietary Allowance more closely matches the actual protein needs of adults with diabetes mellitus [6]. A low-protein diet has been the standard approach for treating end-stage renal disease associated with diabetes, There is some evidence that the progression of diabetic nephropathy is delayed by early protein restriction [7]. Further research into this area is required.
Calories One goal of diet therapy in the management of diabetes mellitus is to assist the person in attaining and maintaining desirable body weight. The amount of calories to be consumed should be prescribed with this goal in mind. Lean persons with type I diabetes mellitus should strive to maintain desirable weight with adequate caloric intake, whereas obese persons with type II diabetes mellitus require special dietary consideration to reduce to a desirable weight. The potential benefits of weight reduction for obese diabetic persons include reduction or elimination of
Fat Almost all risk factors for atherosclerosis occur more frequently in persons with diabetes mellitus. Hyperlipidemia, glycosylation of lipoproteins, platelet dysfunction, arterial wall changes, hyperinsulinemia, hypertension, and obesity all combine in diabetes to accelerate atherosclerosis (Figure 1) [l]. Therefore, maintenance of desirable serum lipid levels is a primary management goal. The traditional diabetes diet, circa 1955, provided 40 percent of energy as carbohydrate, 20 percent protein, and 40 percent fat. This level of carbohydrate
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restriction led to high-fat diets. The metabolic disadvantages of a high-fat diet are clear. In addition to impairing intracellular glucose metabolism, high-fat diets cause insulin resistance, decrease the number of insulin receptors in several tissues, and stimulate rates of gluconeogenesis; high-fat intake also produces hyperlipidemia. Because of the high risk of cardiovascular disease in diabetes, new emphasis is being placed on limiting fat intake. The consensus diabetes diet in 1988 recommends 55 to 60 percent of energy as carbohydrate, 12 to 20 percent protein, and less than 30 percent fat. The specific fat composition of the diet should be essentially that of the American Heart Association diet: daily fat intake to less than 30 percent of total calories consumed, saturated fat to less than 10 percent, polyunsaturated fat to 10 percent, with the remaining calories consisting of monosaturated fat. Total cholesterol intake should be less than 300 mg per day 181. Preferably, total cholesterol intake should remain at less than 200 mg per day. Diets supplemented with guar gum or foods rich in water-soluble fiber are particularly effective in lowering lipid levels. Including one bowl of oat cereal and two oat bran muffins, one-half to one cup cooked dried beans or combinations of these foods daily assures adequate soluble fiber intake [l]. Recent research shows that certain essential fatty acids of the omega-3 class lower serum cholesterol moderately and serum triglyceride levels markedly [9]. These omega-3 fatty acids, popularly known as fish oils, also decrease platelet aggregation [lo]. This may potentially reduce the cardiovascular disease risk in diabetes. Because further data on the effect of fish oil supplementation are needed before recommendations for safety and dosage are determined [ll], a prudent approach suggests eating fish at least once or twice weekly. In an effort to lower the lipid content of the diet, new fat substitutes have been developed and are being tested for safety and efficacy. Olestra, or sucrose polyester, is a nondigestible fat made from sucrose bonded with eight long-chain fatty acids into a molecule too large to be hydrolyzed in the small intestines [12]. For this reason, sucrose polyester contains no calories or cholesterol and may, in fact, bind to cholesterol molecules from other foods in the digestive tract to remove their cholesterol and calories. Sucrose polyester is targeted for use in oils, cooking, frying, fast foods, and snack foods. A very different development in the same category is Simplesse, a fat substitute made using a microparticulation process to convert protein from egg whites and milk into particles less than 3 pm in diameter, which the tongue perceives as the creamy sensation of fat. Because this product is derived from protein, it contains 1.5 calories/g versus 9 calories/g of fat. The manufacturers projected use includes dairy products and oil-based products such as salad dressings [13]. Both fat substitutes require Food and Drug Administration (FDA) approval, so common application in the diabetes diet will not occur for some time. The potential usefulness of products such as sucrose polyester and Simplesse lies in their effectiveness in assisting persons in staging dietary changes to reach realistic nutrition goals.
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Alternative Sweeteners
A continuing area of controversy in the nutrition management of diabetes mellitus is the use of various nutritive and non-nutritive sweeteners. There is a lack of research demonstrating a definite benefit in improving dietary adherence or weight reduction. In fact, although the use of artificial sweetener has more than tripled from 1965 to 1985, per-capita consumption of sugar has risen 14 percent to 129.8 pounds in the same time frame 1141. However, many practitioners believe that the availability of alternative sweeteners is beneficial for the improvement of quality of life. The currently available nutritive sweeteners include fructose and the sugar alcohols such as sorbitol and mannitol. Fructose offers advantages over sucrose for diabetic persons because it tastes sweeter, is metabolized without insulin, and does not produce as rapid a rise in blood glucose levels as other simple carbohydrates [151. The sugar alcohols are absorbed slowly from the gastrointestinal tract and have less influence on blood glucose and insulin levels than glucose, sucrose, or fructose [16]. Possible side effects of sorbitol and mannitol include osmotic diarrhea, abdominal discomfort, and gas and malabsorption, even with relatively low oral doses. Health aspects of sugar alcohols are currently being investigated by the FDA. Saccharin, aspartame, and cyclamate comprise the non-nutritive sweeteners. Saccharin was the first synthetic sugar substitute and may be associated with increased risk for bladder cancer. At this time, a prudent view would be that higher-than-normal risk groups, such as children and pregnant women, limit their use of saccharin. Aspartame was approved for use as a food additive in 1981. It is actually a nutritive protein sweetener, composed of phenylalanine and aspartic acid. Aspartame does not alter glycemie control of diabetes mellitus, but undue alarm has been raised concerning issues of safety. The FDA has set 50 mgikg body weight as an acceptable daily intake 1171. In ongoing evaluations by the FDA and other regulatory agencies, aspartame appears reasonably safe for persons without phenylketonuria. Cyclamate is no longer available in the United States since a 1970 report from studies finding that large doses given to laboratory rats were associated with increased risk of bladder cancer. At this point, no recommendation for use can be made, and FDA investigation into safety issues continues. Salt Intake
Generally, Americans eat more salt than the recommended level of less than 3,000 mg per day, and concern with hypertension and its development in people with diabetes mellitus appears well-grounded. Control of hypertension is one of the initial steps in the management of the microvascular and macrovascular complications associated with diabetes mellitus [18]. A modest restriction in dietary sodium intake is believed to be sensible, with a more severe restriction required in some cases of hypertension. Alcohol
Alcohol in moderation poses no greater health risk for diabetic than nondiabetic persons provided sensible guidelines are followed. The energy contribution
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P’O.01 CARBOHYDRATE:
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1 HCHF
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Figure 2. Comparison of insulin requirements and carbohydrate:insulin ratio (expressed as g of carbohydrate per unit of insulin) on control or LCLF and HCHF diets in subjects with type I diabetes mellitus.
of alcohol should not exceed 6 percent of daily intake, which translates into no more than two glasses of dry wine or one mixed drink or two beers daily [19]. Specific concerns for persons with diabetes include the habit-forming and toxic effects of alcohol, errors in insulin or oral hypoglycemic use, missed meals, hypoglycemia due to alcohol inhibition of hepatic glucose output, excessive energy intake, the possible unpleasant reaction of alcohol with oral sulfonylurea agents, and stimulation of hypertriglyceridemia [ZO]. Vitamins and Minerals A goal of nutrition therapy of diabetes is a plan that provides optimal amounts and varieties of nutrients. Evidence that persons with diabetes mellitus have unique needs that warrant vitamin or mineral supplementation has not been found [2]. Therefore, recommendations in this area are the same as for the general population. Special consideration for vitamin and mineral supplementation should be given to type II patients receiving very low-calorie diets for weight reduction [21]. OTHER CONSIDERATIONS Fiber The therapeutic value of fiber for diabetic persons has become evident over the last decade. Attention was focused on the role of fiber in the mid-1970s when Trowel1 [22] formulated the dietary fiber hypothesis of the origin of diabetes. Other researchers then began to explore the beneficial consequences that increased amounts of dietary fiber may have for persons with diabetes. In 1976, Jenkins and associates [23] reported that fiber supplementation with guar or pectin, in comparison with no fiber supplementation, reduced postprandial glycemic responses and serum insulin responses of lean subjects with diabetes. Until recently, no acceptable purified fiber preparation was commercially available for clinical use. Several new short-term studies show beneficial effects from adding
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varying amounts of guar to the regular meal plan, but limitations in these studies have been noted [24]. Another approach to the study of the effects of fiber in diabetes involves supplementing the traditional diabetic diet with ordinary foods high in fiber content. In 1974, we developed the high-carbohydrate, high-fiber (HCF) diet at the Veterans Administration Medical Center in Lexington, Kentucky. This diet supplied 70 percent of energy as carbohydrate, 18 percent protein, 12 percent fat, and about 35 g/1,000 kcal of fiber. When fed this diet, lean persons with diabetes had improved glucose concentration, decreased insulin requirements, and decreased cholesterol concentration [251. Those with type II diabetes obtained greater benefits, with observed reductions of insulin requirements of 25 to 100 percent. As part of follow-up, a maintenance diet for home use was developed. This maintenance diet is very similar to the 1988 version of the traditional American Diabetes Association diet, and most persons have tolerated it well over the long term, while maintaining improved glycemic and lipid control 1261. The question has been raised as to whether this improved control is the result of the increased fiber content, increased carbohydrate content, or a synergistic effect of both 151. Available data do not permit definitive evaluation of these possibilities. To objectively assess changes in insulin requirements in response to HCF diets, we used an artificial pancreas (Biostator) to study nine lean type I diabetic subjects. These subjects entered the metabolic ward and received a weight-maintaining low-carbohydrate, low-fiber (LCLF) diet that provided 39 percent of energy as carbohydrate and 10 g of fiber per day for one week. They then entered a Biostator study and were randomly allocated to either the LCLF diet or highcarbohydrate, high-fiber (HCHF) diet that provided 70 percent of energy as carbohydrate and 70 g of fiber per day for four weeks, ending with a second Biostator study. After a six-week outpatient washout period, subjects re-entered the metabolic ward for the alternate diet for four weeks, ending with another Biostator study. The results of the study showed that total, mealrelated, and basal insulin requirements were lower on the HCHF diet than the control diet despite a carbohydrate intake of l.&fold higher on the HCHF diet. Of greater interest, however, was the more than 2.2fold increase in the carbohydrate/insulin ratio on the HCHF diet, indicating that these type I diabetic subjects disposed of more than twice as much earbohydrate per unit of insulin with the HCHF diet than with the control diet [2’7]. Further studies are required to determine to what extent this increased insulin sensitivity is related to the increased carbohydrate and reduced fat intake and to what extent it is related to increased fiber intake. Further studies are also required to determine if this primarily represents an ‘increase in muscle sensitivity to insulin as our previous work in healthy subjects indicates [28]. Figure 2 illustrates these results. Research into the mechanisms responsible for the favorable effects continues. HCHF diets improve glucose metabolism without increasing insulin secretion. These diets lower fasting serum and peripheral insulin concentrations and are associated with a twofold in-
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Figure 3. A, Glycemic response of healthy per. sons to 50 g of carbohydrate from new potatoes or kidney beans. Data are from [35]. B, Glycemic response of healthy persons to 50 g of glucose, sucrose, or fructose. Data are from Anderson, unpublished. Reprinted with permission from
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WI. crease in insulin sensitivity as estimated by the euglycemic clamp technique. Mechanisms to explain the hypocholesterolemic effects of HCHF diets are still under investigation [29]. Current estimates of the dietary fiber intake of adults in the United States range from approximately 11 to 23 g per day [301. Because fiber appears to have distinct benefits for people with diabetes mellitus, a goal of increasing intake up to 40 g per day or 15 to 25 g/1,000 kcal food should be beneficial. This increase should focus on both soluble and insoluble forms of fiber-rich foods rather than fiber supplements [311. It is important to note that the potential impact of highfiber diets on calcium, trace mineral metabolism, and vitamins needs to be more closely investigated [30]. McIvor et al [321 examined the safety of long-term guar supplementation and found no adverse effects on nutritional status following intake of 30 g of guar daily for 16 weeks. Adequate fluid intake should accompany increased dietary fiber intake in order to derive the beneficial effects of fiber, as well as to avoid the small potential risk of gastrointestinal obstruction [33]. Because high-fiber diets act to lower blood glucose concentration and insulin requirements, careful attention must be paid to insulin dose to avoid hypoglycemia when fiber intake is increased. Therefore, insulin dose should be decreased by 10 percent and oral agent dose by one-third to one-half when a high-fiber diet is initiated [341. Glycemic Index
The glycemic index is an attempt to classify individual foods by the extent to which they raise blood glucose levels. This is an interesting concept, based on the observation that simple carbohydrates from commonly used foods tend to raise blood glucose levels more than do complex carbohydrates from starchy foods (Figure 3). For example, 50 g of carbohydrate from new potatoes has a glycemic index of ‘70, whereas 50 g of carbohydrate from kidney beans provides a glycemic index of approximately 29 [35]. Many factors interact to influence the glycemic response to food. The physical form of food affects the rate of absorption and subsequent rise in glucose levels, as does the rate at which the food is ingested and digested. Foods such as legumes, which are digested less rapidly than other
carbohydrate foods, cause a slower and lower glycemic response. The fiber content of the diet per se does not seem to be the major factor in determining glycemic response, but foods with a high soluble fiber content seem to have a lower glycemic index rating [36]. Because of the complexities in teaching and applying the glycemic index to individual patients, practical application is difficult. However, the concept has stimulated new research into the area of nutritional management of diabetes mellitus that may shape the future of diet therapy.
PRACTICALAPPLICATIONS As new concepts in the science of nutrition for diabetes are clarified, the challenge of putting these concepts into practice remains. Given the general guidelines of a prudent nutrition plan appropriate for the management of diabetes-generous amounts of complex carbohydrate and fiber with restrictions of fat and cholesterol-what can be done to develop a dietary approach that will be suited to individual patients and contribute to the control of diabetes? A critical element in diet effectiveness over the long term is individualization. Flexibility within the guidelines previously outlined should be encouraged to promote adherence. The best nutrition plans are not effective if people do not follow them. Initially, the physician or health care team members should realistically assess the capabilities of diabetic patients and their support systems. The registered dietitian can then develop a specific nutrition plan based on current eating habits, desirable weight estimates, and an education strategy suited to the individual patient. A phased plan for nutrition counseling may begin with the survival phase, shortly after diagnosis, when basics of meal planning are taught. Thereafter, a goal-oriented progression should take place, through phases of increasing information acquisition, incorporation of information into new knowledge and skills, a program of continuing education and reinforcement, and an ultimate goal of promoting positive behavioral change [3’71. The American Diabetes Association/American Dietetic Association Exchange Lists were first released in 1950 and have remained the most acceptable, universal method of meal planning. However, it is unreal-
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istic to suppose that this approach is appropriate for all persons with diabetes mellitus. Alternatives include guidelines such as the United States Dietary Guidelines and Basic Four Food Groups, which provide basic principles of nutrition and diabetes management that can serve a wide spectrum of people because they offer both simplicity and flexibility. HCF Exchanges have been developed to serve as a high-fiber alternatiye to the American Diabetes Association Exchanges [38]. The HCF Nutrition Plan emphasizes foods high in carbohydrate and fiber content and low in fat and cholesterol. To meet these goals, the Exchanges include a Bean group and Starch group.; the traditional Meat exchange group is entitled Proteins to shift the emphasis from meat and highlight other low-fat protein sources such as fish. Counting options, such as Total Available Glucose and the Point System represent other structured meal planning approaches. Menu plans can serve as either the single educational tool for persons of low literacy or as an adjunct to diabetes nutrition guidelines for the self-directed, motivated people [39]. Nutrition instruction and counseling are central to the control of diabetes. Sixty-six percent of patients with diabetes do not possess the requisite knowledge to follow a prescribed diet and do not know what caloric intake has been prescribed [40]. Although adherence to diet plans is notoriously poor, the team approach to education and follow-up can greatly enhance effectiveness.
COMMENTS Diet remains the cornerstone of management for all types of diabetes mellitus. Good glycemic control, desirable serum lipid levels, and the reduction of risk for metabolic, microvascular, and macrovascular complications are the key goals for a diabetes nutrition plan. Recent developments in the rapidly changing field of nutrition have raised questions about the optimal carbohydrate, protein, and fat intake for persons with diabetes mellitus, as well as the use of fiber and the role of the glycemic index. Considerable clinical and experimental data have emerged to support recommendations of a diet generous in complex carbohydrate and fiber and restricted in fat and cholesterol. Current nutrition recommendations for persons with diabetes include all the nutrition principles of a prudent or health-promoting diet. Individual caloric needs should be evaluated to assist the patient in attaining and maintaining desirable body weight. Diets high in complex carbohydrate and fiber improve glycemic control, reduce insulin requirements, and lower serum cholesterol concentrations. Dietary fiber offers distinct health advantages for pertions with diabetes. Because almost all risk factors for atherosclerosis occur more frequently in persons with diabetes mellitus, new emphasis is being placed on limiting fat intake to less than 30 percent of total calories consumed. Alternative sweeteners, whether nutritive or nonnutritive, may be recommended if they are safe and compatible with the nutrition plan. The glycemic index attempts to categoriie foods by the extent to which they raise blood glucose levels. Although this concept may have practical applications in diet planning, further investigation should prove helpful in defining its role.
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The effects of diet components have been extensively studied, and the importance of individualized and flexible nutrition plans to promote adherence should receive further emphasis in future areas of research. Nutrition instruction and counseling are central to the control of diabetes. Persons with diabetes can change their eating patterns and closely adhere to a diet plan if the entire health care ‘team is enthusiastic, supportive, and instructive.
REFERENCES 1. Anderson JW, Gustafson NJ: Nutrition management of hyperlipidemia in diabetes. Pratt Diabetol 1987; 6: 16-20. 2. American Diabetes Association: Nutritional recommendations and principles for individuals with diabetes mellitus: 1986. Diabetes Care 1987; 10: 126-132. 3. Hansen BC: Dietary considerations for obese diabetic subjects. Diabetes Care 1988; 11: 183-188. 4. Henry RR, Wiest-Kent TA, Scheaffer L, eta/: Metabolic consequences of very-low.calorie diet therapy in non.insulin.dependent diabetic and non-diabetic subjects, Diabetes 1986; 35: 155-164. 5. Hollenbeck CB, Coulston AM, Reaven GM: Glycemic effects of carbohydrates: a different perspective. Diabetes Care 1986; 9: 641-647. 6. Wylie-Rosett J: Evaluation of protein in dietary management of diabetes mellitus. Diabetes Care 1988; 11: 143-148. 7. Rosman JB, TerWee PM, Meijer S, et al: Prospective randomized study of early protein restriction in chronic renal failure. Lancet 1984; II: 1291-1296. 6. Nutrition Committee, American Heart Association: Dietary guidelines for healthy American adults. Circulation 1988; T7: 721A-724A. 9. Phillipson BE, Rothrock DW, Connor WE, Harris WS, lllingworth DR: Reduction of plasma lipids, lipoproteins and apoproteins by dietary fish oils in patients with hypertriglyceride mia. N Engl J Med 1985; 312: 1210-1216. 10. von Schacky C, Fischer S, Weber PC: Long-term effects of dietary marine omega3 fatty acids upon plasma and cellular lipids, platelet function and eicosaniod formation in humans. J Clin Invest 1985; 76: 1626-1631. 11. Herold PM, Kinsella JE: Fish oil consumption and decreased risk of cardiovascular disease: a comparison of findings from animal and human feeding trials. Am J Clin Nutr 1986; 43: 566-598. 12. Crouse JR, Grundy SM: Effects of sucrose polyester on cholesterol metabolism in man. Metabolism 1979; 28: 994-1000. 13. The NutraSweet Company: Simplesse product information. January 27, 1988. 14. United States Department of Agriculture, 1986. 15. Craoo PA. Kolterman OG. Olesfskv JM: Effects of oral fructose in normal. diabetic and impaired glucose tolerance subjects-Diabetes Care 1980; 3: 575-582. 16. Crapo PA: Use of alternative sweeteners in diabetic diet. Diabetes Care 1988; 11:
174-182. 17. Food and Drug Administration: Aspartame: commissioner’s final decision, Fed Regist 1981; 46: 38285-38308. 16. Franz MJ: Recent revisions in nutrition guidelines for persons with diabetes, Int Med
1988; 9: 159-168. 19. Lieber CS: To drink (moderately) or not to drink? N Engl J Med 1984; 310: 846-848. 20. Anderson JW: Nutrition management of diabetes mellitus. In: Shils ME, Young VR, eds. Modern nutrition in health and disease. Philadelohia: Lea & Febieer. 1988: 1201-1229. 21. Amatruda JM, Biddle TL, Patton ML, Lockwood DH: Vigorous sbpplemeiiation of a hypocaloric diet prevents cardiac arrhythmias and mineral depletion. Am J Med 1983; 74:
1016-1022. 22. Trowel1 HC: Dietary-fiber hypothesis of the etiology of diabetes mellitus. Diabetes
1975; 24: 762-765. 23. Jenkins DJA, Goff DV, Leeds AR, et al: Unabsorbable carbohydrates and diabetes: decreased post.prandial hyperglycemia. Lancet 1976; II: 172-174. 24. Fuessl H, Adrian TE, BacareseHamilton Al, Bloom SR: Effects of guar on plasma glucose and gut hormone response in type II diabetics. In: Proceedings of the Spring Meeting of the British Diabetes Association, Oxford, 1985; 59. 25. Kiehm TG, Anderson JW, Ward K: Beneficial effects of a high carbohydrate, high fiber diet on hyperglycemic diabetic men. Am J Clin Nutr 1976; 29: 895-899. 26. Story L, Anderson JW, Chen WL, et at Adherence to high-carbohydrate, high-fiber diets: long term studies of non-obese diabetic men. J Am Diet Assoc 1985; 85: 1105-
1110. 27. Anderson JW, Zeigler J, Deakins D: High fiber diets increase insulin sensitivity and carbohydrate disposal in type I diabetic individuals (abstr). Diabetes 1988; 37: 11A. 28. Fukagawa NK, Minaker KL, Hageman G, Young VR, Anderson JW: High.carbohydrate, high fiber’diets increase peripheral insulin sensitivity of healthy young men (abstr). Clin Res
1984; 32: 130. 29. Anderson JW: Nutrition management of metabolic conditions. Lexingron, Kentucky: HCF Diabetes Foundation, 1986. 30. Federation of American Societies for Experimental Biology: Physiological effects and health consequences of dietary fiber. Pilch SM, ed. Bethesda, Maryland: Life Sciences Research Office, 1987.
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SYMPOSIUM 31. Vinik Al, Jenkins DJA: Dietary fiber in the management of diabetes. Diabetes Care 1988; 11: 160-173. 32. Mclvor ME, Cummings CC, Mendeloff Al: Long term ingestion of guar gum IS not toxic in patients with non-insulin dependent diabetes mellitus. Am J Clin Nutr 1985; 41: 891894. 33. Klurfeld DM: The role of dietary fiber in gastrointestinal disease. J Am Diet Assoc 1987; 87: 1172-11777. 34. Anderson JW, Gustafson NJ, Bryant CA, Tietyen-Clark J: Dietary fiber and diabetes: a comprehensive review and practical application. J Am Diet Assoc 1987; 87: 11891197. 35. Jenkins DJA, Taylor RH, Wolever TMS: The diabetic diet, dietary carbohydrate and
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differences in digestibrlity. Diabetologia 1982; 23: 477-484. 36. Franz MJ: Evaluating the glycemic response to carbohydrates. Clin Diab 1986; 6: 129-141. 37. Franz M, Krosnick A, Maschak-Carey BJ, et a/: Goals for diabetes education. Alexandria, Virginia: American Diabetes Association, 1986. 38. Anderson JW: HCF exchanges-the high carbohydrate.high fiber (HCF) nutrition plan. Lexington, Kentucky: HCF Diabetes Foundation, 1987. 39. Green JA: Diabetes nutritional management: a need for meal planning alternatives. The Diabetes Educator 1987; 13: 145-147. 40. American Association of Diabetes Educators: Understanding diabetes mellitus. Continuing Education Self-Study Program, Module 4, 1984.
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iabetes mellitus is a complex metabolic disorder D affecting metabolism of carbohydrates, fats, and other nutrients. Appropriate nutrition management is
Diet remains the cornerstone in the management of diabetes mellitus. A prudent nutrition plan reduces the exaggerated risk for atherosclerotic heart disease and metabolic complications of diabetes by improving lipid and glycemic control. The current consensus diabetes diet recommends 55 to 60 percent of energy as carbohydrate, 12 to 20 percent as protein, and less than 30 percent fat. Total cholesterol intake should be less than 300 mg per day. Fiber appears to have distinct benefits in improving glucose and lipid levels; therefore, an intake of up to 40 g per day or 15 to 25 g/1,000 kcal of food is recommended. Other considerations in meal planning for diabetes include alternative sweeteners, salt intake, alcohol consumption, and vitamin and mineral needs. Individualized and flexible nutrition plans, designed within established guidelines, promote adherence. Persons with diabetes can change their eating patterns and closely adhere to a diet plan if the entire health care team is enthusiastic, supportive, and instructive.
essential for restoring and maintaining a normal metabolic state. In addition to reducing the risk for the metabolic complications of diabetes, a prudent diet also reduces risk for atherosclerotic cardiovascular disease. Diabetic persons are at distinctly higher risk for coronary heart disease and cerebrovascular disease and at substantially higher risk for peripheral vascular disease than nondiabetic persons. A prudent diet favorably affects, reduces, or reverses these risk factors for atherosclerotic vascular disease: hypercholesterolemia, hypertension, hypertriglyceridemia, obesity, abnormally sticky platelets, hyperinsulinemia, and hyperglycemia. The last decade introduced several new considerations to the nutrition management of diabetes. In the carbohydrate arena, we have dietary fiber, an endorsement of a generous complex carbohydrate intake, new insights into the glycemic effects of simple and complex carbohydrate, and new artificial sweeteners. Relative to fats as a nutrient., available are fish oils and fat substitutes, and there 1s a new appreciation of monosaturated fats. We now have to consider the role that the amount and type of protein may have in the risk for renal disease. Thus, diet remains the cornerstone in the management of diabetes as it has for over two millennia. Intelligent adherence to a suitable nutrition plan not only reduces risk for metabolic complications by enhanced glycemic control, but also reduces risk for atherosclerotic cardiovascular disease, the major risk for decreased quality of life and premature death.
GOALS Recommendations for nutrition management of diabetes mellitus should be based on achieving one underlying aim-a healthy patient with a full lifestyle and normal longevity. Specific as well as general goals aid in accomplishing this aim. Fundamentally, the primary purpose of nutrition therapy is to achieve normal or physiologic blood glucose levels by optimizing glucose use, normalizing glucose production, and enhancing insulin sensitivity. Persons with diabetes die from coronary vessel disease two to three times more frequently than do nondiabetic persons. Since average serum lipid levels are higher in diabetic than non-diabetic persons? maintaining desirable plasma lipid levels is a specific goal that may retard the development of atherosclerosis I
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From the Department of Endocrinology and Metabolism, Veterans Administration Medical Center, and the Uwersity of Kentucky, Lexington, Kentucky. Requests for reprints should be addressed to Dr. James W. Anderson, Veterans AdminIstration Medical Center, Medical Services IIIC, Cooper Drive, Lexington, Kentucky 40511. I
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exogenous insulin requirements, an increase in life expectancy, and improved health [3]. Any person following a weight-loss program should be closely supervised by health professionals. Ideally, such a program would be nutritionally balanced with a calorie reduction of 500 to 1,000 kcal below normal daily levels. The key to sustaining successful weight loss is a long-term behavioral approach in follow-up. In some cases, a more marked caloric reduction may be needed to produce a more rapid weight loss. Very low-calorie diets have been studied in a small number of persons with type II diabetes with reportedly safe and effective results in the short term [4]. Concern remains about the long-term use of very low-calorie diets, particularly in the area of endogenous protein metabolism.
gure 1. Influence of nutrition on major risk factors contributing to atheroscleros diabetes.
fully understood, it seems logical that good management will reduce the risk for metabolic, macrovascular, and microvascular complications. These specific goals are founded on general nutrition recommendations for overall health and wellbeing. The diabetes diet must provide appropriate amounts and varieties of nutrients. It should assist the person with diabetes in attaining and maintaining desirable body weight while meeting energy needs in a timely manner. Flexibility within specific recommendations, particularly in the area of food preferences and availability, will promote adherence to the nutrition plan. Unique physiologic requirements and therapeutic modifications for medical conditions should be considered as general goals for nutrition management of diabetes mellitus.
Carbohydrate Recommendations for the amount of carbohydrate to provide in the diabetic diet have sparked controversy as far back as the 16th century B.C., when Egyptians prescribed diets with high levels of carbohydrate to combat the dissolving of flesh into the urine. Since that time, medical science has suggested that the consumption of carbohydrate be severely restricted. This viewpoint became liberalized over time to the point that in 1988 we recommend the carbohydrate content of the diet be 55 to 60 percent of total calories consumed. Diets high in complex carbohydrate and fiber improve glycemic control and lower serum cholesterol concentrations. Although concentrated carbohydrate may worsen glycemic control [5] and promote weight gain, the 1985 American Diabetes Association Task Force on Nutrition suggested that “modest amounts of sucrose and other refined sugars may be acceptable, contingent on metabolic control and body weight.”
Due to new and emerging information regarding the effects of diet on blood glucose concentration, the role of nutrition in the management of diabetes mellitus continues to be examined. In 1985, the American Diabetes Association appointed the Task Force on Nutrition to update guidelines and formulate new recommendations for diet therapy. The findings of the Task Force were summarized and published [21. However, new facts in the field are evolving rapidly and continued updates and revisions are required. The following is a summary of current knowledge in key areas.
Protein The primary function of protein in the diet is for growth and tissue maintenance. Although the nutritional recommendation for protein in the diabetes diet is 12 to 20 percent of calories, this amount exceeds the adult Recommended Dietary Allowance of 0.8 g/kg body weight. The Recommended Dietary Allowance more closely matches the actual protein needs of adults with diabetes mellitus [6]. A low-protein diet has been the standard approach for treating end-stage renal disease associated with diabetes, There is some evidence that the progression of diabetic nephropathy is delayed by early protein restriction [7]. Further research into this area is required.
Calories One goal of diet therapy in the management of diabetes mellitus is to assist the person in attaining and maintaining desirable body weight. The amount of calories to be consumed should be prescribed with this goal in mind. Lean persons with type I diabetes mellitus should strive to maintain desirable weight with adequate caloric intake, whereas obese persons with type II diabetes mellitus require special dietary consideration to reduce to a desirable weight. The potential benefits of weight reduction for obese diabetic persons include reduction or elimination of
Fat Almost all risk factors for atherosclerosis occur more frequently in persons with diabetes mellitus. Hyperlipidemia, glycosylation of lipoproteins, platelet dysfunction, arterial wall changes, hyperinsulinemia, hypertension, and obesity all combine in diabetes to accelerate atherosclerosis (Figure 1) [l]. Therefore, maintenance of desirable serum lipid levels is a primary management goal. The traditional diabetes diet, circa 1955, provided 40 percent of energy as carbohydrate, 20 percent protein, and 40 percent fat. This level of carbohydrate
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restriction led to high-fat diets. The metabolic disadvantages of a high-fat diet are clear. In addition to impairing intracellular glucose metabolism, high-fat diets cause insulin resistance, decrease the number of insulin receptors in several tissues, and stimulate rates of gluconeogenesis; high-fat intake also produces hyperlipidemia. Because of the high risk of cardiovascular disease in diabetes, new emphasis is being placed on limiting fat intake. The consensus diabetes diet in 1988 recommends 55 to 60 percent of energy as carbohydrate, 12 to 20 percent protein, and less than 30 percent fat. The specific fat composition of the diet should be essentially that of the American Heart Association diet: daily fat intake to less than 30 percent of total calories consumed, saturated fat to less than 10 percent, polyunsaturated fat to 10 percent, with the remaining calories consisting of monosaturated fat. Total cholesterol intake should be less than 300 mg per day 181. Preferably, total cholesterol intake should remain at less than 200 mg per day. Diets supplemented with guar gum or foods rich in water-soluble fiber are particularly effective in lowering lipid levels. Including one bowl of oat cereal and two oat bran muffins, one-half to one cup cooked dried beans or combinations of these foods daily assures adequate soluble fiber intake [l]. Recent research shows that certain essential fatty acids of the omega-3 class lower serum cholesterol moderately and serum triglyceride levels markedly [9]. These omega-3 fatty acids, popularly known as fish oils, also decrease platelet aggregation [lo]. This may potentially reduce the cardiovascular disease risk in diabetes. Because further data on the effect of fish oil supplementation are needed before recommendations for safety and dosage are determined [ll], a prudent approach suggests eating fish at least once or twice weekly. In an effort to lower the lipid content of the diet, new fat substitutes have been developed and are being tested for safety and efficacy. Olestra, or sucrose polyester, is a nondigestible fat made from sucrose bonded with eight long-chain fatty acids into a molecule too large to be hydrolyzed in the small intestines [12]. For this reason, sucrose polyester contains no calories or cholesterol and may, in fact, bind to cholesterol molecules from other foods in the digestive tract to remove their cholesterol and calories. Sucrose polyester is targeted for use in oils, cooking, frying, fast foods, and snack foods. A very different development in the same category is Simplesse, a fat substitute made using a microparticulation process to convert protein from egg whites and milk into particles less than 3 pm in diameter, which the tongue perceives as the creamy sensation of fat. Because this product is derived from protein, it contains 1.5 calories/g versus 9 calories/g of fat. The manufacturers projected use includes dairy products and oil-based products such as salad dressings [13]. Both fat substitutes require Food and Drug Administration (FDA) approval, so common application in the diabetes diet will not occur for some time. The potential usefulness of products such as sucrose polyester and Simplesse lies in their effectiveness in assisting persons in staging dietary changes to reach realistic nutrition goals.
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Alternative Sweeteners
A continuing area of controversy in the nutrition management of diabetes mellitus is the use of various nutritive and non-nutritive sweeteners. There is a lack of research demonstrating a definite benefit in improving dietary adherence or weight reduction. In fact, although the use of artificial sweetener has more than tripled from 1965 to 1985, per-capita consumption of sugar has risen 14 percent to 129.8 pounds in the same time frame 1141. However, many practitioners believe that the availability of alternative sweeteners is beneficial for the improvement of quality of life. The currently available nutritive sweeteners include fructose and the sugar alcohols such as sorbitol and mannitol. Fructose offers advantages over sucrose for diabetic persons because it tastes sweeter, is metabolized without insulin, and does not produce as rapid a rise in blood glucose levels as other simple carbohydrates [151. The sugar alcohols are absorbed slowly from the gastrointestinal tract and have less influence on blood glucose and insulin levels than glucose, sucrose, or fructose [16]. Possible side effects of sorbitol and mannitol include osmotic diarrhea, abdominal discomfort, and gas and malabsorption, even with relatively low oral doses. Health aspects of sugar alcohols are currently being investigated by the FDA. Saccharin, aspartame, and cyclamate comprise the non-nutritive sweeteners. Saccharin was the first synthetic sugar substitute and may be associated with increased risk for bladder cancer. At this time, a prudent view would be that higher-than-normal risk groups, such as children and pregnant women, limit their use of saccharin. Aspartame was approved for use as a food additive in 1981. It is actually a nutritive protein sweetener, composed of phenylalanine and aspartic acid. Aspartame does not alter glycemie control of diabetes mellitus, but undue alarm has been raised concerning issues of safety. The FDA has set 50 mgikg body weight as an acceptable daily intake 1171. In ongoing evaluations by the FDA and other regulatory agencies, aspartame appears reasonably safe for persons without phenylketonuria. Cyclamate is no longer available in the United States since a 1970 report from studies finding that large doses given to laboratory rats were associated with increased risk of bladder cancer. At this point, no recommendation for use can be made, and FDA investigation into safety issues continues. Salt Intake
Generally, Americans eat more salt than the recommended level of less than 3,000 mg per day, and concern with hypertension and its development in people with diabetes mellitus appears well-grounded. Control of hypertension is one of the initial steps in the management of the microvascular and macrovascular complications associated with diabetes mellitus [18]. A modest restriction in dietary sodium intake is believed to be sensible, with a more severe restriction required in some cases of hypertension. Alcohol
Alcohol in moderation poses no greater health risk for diabetic than nondiabetic persons provided sensible guidelines are followed. The energy contribution
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Figure 2. Comparison of insulin requirements and carbohydrate:insulin ratio (expressed as g of carbohydrate per unit of insulin) on control or LCLF and HCHF diets in subjects with type I diabetes mellitus.
of alcohol should not exceed 6 percent of daily intake, which translates into no more than two glasses of dry wine or one mixed drink or two beers daily [19]. Specific concerns for persons with diabetes include the habit-forming and toxic effects of alcohol, errors in insulin or oral hypoglycemic use, missed meals, hypoglycemia due to alcohol inhibition of hepatic glucose output, excessive energy intake, the possible unpleasant reaction of alcohol with oral sulfonylurea agents, and stimulation of hypertriglyceridemia [ZO]. Vitamins and Minerals A goal of nutrition therapy of diabetes is a plan that provides optimal amounts and varieties of nutrients. Evidence that persons with diabetes mellitus have unique needs that warrant vitamin or mineral supplementation has not been found [2]. Therefore, recommendations in this area are the same as for the general population. Special consideration for vitamin and mineral supplementation should be given to type II patients receiving very low-calorie diets for weight reduction [21]. OTHER CONSIDERATIONS Fiber The therapeutic value of fiber for diabetic persons has become evident over the last decade. Attention was focused on the role of fiber in the mid-1970s when Trowel1 [22] formulated the dietary fiber hypothesis of the origin of diabetes. Other researchers then began to explore the beneficial consequences that increased amounts of dietary fiber may have for persons with diabetes. In 1976, Jenkins and associates [23] reported that fiber supplementation with guar or pectin, in comparison with no fiber supplementation, reduced postprandial glycemic responses and serum insulin responses of lean subjects with diabetes. Until recently, no acceptable purified fiber preparation was commercially available for clinical use. Several new short-term studies show beneficial effects from adding
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varying amounts of guar to the regular meal plan, but limitations in these studies have been noted [24]. Another approach to the study of the effects of fiber in diabetes involves supplementing the traditional diabetic diet with ordinary foods high in fiber content. In 1974, we developed the high-carbohydrate, high-fiber (HCF) diet at the Veterans Administration Medical Center in Lexington, Kentucky. This diet supplied 70 percent of energy as carbohydrate, 18 percent protein, 12 percent fat, and about 35 g/1,000 kcal of fiber. When fed this diet, lean persons with diabetes had improved glucose concentration, decreased insulin requirements, and decreased cholesterol concentration [251. Those with type II diabetes obtained greater benefits, with observed reductions of insulin requirements of 25 to 100 percent. As part of follow-up, a maintenance diet for home use was developed. This maintenance diet is very similar to the 1988 version of the traditional American Diabetes Association diet, and most persons have tolerated it well over the long term, while maintaining improved glycemic and lipid control 1261. The question has been raised as to whether this improved control is the result of the increased fiber content, increased carbohydrate content, or a synergistic effect of both 151. Available data do not permit definitive evaluation of these possibilities. To objectively assess changes in insulin requirements in response to HCF diets, we used an artificial pancreas (Biostator) to study nine lean type I diabetic subjects. These subjects entered the metabolic ward and received a weight-maintaining low-carbohydrate, low-fiber (LCLF) diet that provided 39 percent of energy as carbohydrate and 10 g of fiber per day for one week. They then entered a Biostator study and were randomly allocated to either the LCLF diet or highcarbohydrate, high-fiber (HCHF) diet that provided 70 percent of energy as carbohydrate and 70 g of fiber per day for four weeks, ending with a second Biostator study. After a six-week outpatient washout period, subjects re-entered the metabolic ward for the alternate diet for four weeks, ending with another Biostator study. The results of the study showed that total, mealrelated, and basal insulin requirements were lower on the HCHF diet than the control diet despite a carbohydrate intake of l.&fold higher on the HCHF diet. Of greater interest, however, was the more than 2.2fold increase in the carbohydrate/insulin ratio on the HCHF diet, indicating that these type I diabetic subjects disposed of more than twice as much earbohydrate per unit of insulin with the HCHF diet than with the control diet [2’7]. Further studies are required to determine to what extent this increased insulin sensitivity is related to the increased carbohydrate and reduced fat intake and to what extent it is related to increased fiber intake. Further studies are also required to determine if this primarily represents an ‘increase in muscle sensitivity to insulin as our previous work in healthy subjects indicates [28]. Figure 2 illustrates these results. Research into the mechanisms responsible for the favorable effects continues. HCHF diets improve glucose metabolism without increasing insulin secretion. These diets lower fasting serum and peripheral insulin concentrations and are associated with a twofold in-
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Figure 3. A, Glycemic response of healthy per. sons to 50 g of carbohydrate from new potatoes or kidney beans. Data are from [35]. B, Glycemic response of healthy persons to 50 g of glucose, sucrose, or fructose. Data are from Anderson, unpublished. Reprinted with permission from
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WI. crease in insulin sensitivity as estimated by the euglycemic clamp technique. Mechanisms to explain the hypocholesterolemic effects of HCHF diets are still under investigation [29]. Current estimates of the dietary fiber intake of adults in the United States range from approximately 11 to 23 g per day [301. Because fiber appears to have distinct benefits for people with diabetes mellitus, a goal of increasing intake up to 40 g per day or 15 to 25 g/1,000 kcal food should be beneficial. This increase should focus on both soluble and insoluble forms of fiber-rich foods rather than fiber supplements [311. It is important to note that the potential impact of highfiber diets on calcium, trace mineral metabolism, and vitamins needs to be more closely investigated [30]. McIvor et al [321 examined the safety of long-term guar supplementation and found no adverse effects on nutritional status following intake of 30 g of guar daily for 16 weeks. Adequate fluid intake should accompany increased dietary fiber intake in order to derive the beneficial effects of fiber, as well as to avoid the small potential risk of gastrointestinal obstruction [33]. Because high-fiber diets act to lower blood glucose concentration and insulin requirements, careful attention must be paid to insulin dose to avoid hypoglycemia when fiber intake is increased. Therefore, insulin dose should be decreased by 10 percent and oral agent dose by one-third to one-half when a high-fiber diet is initiated [341. Glycemic Index
The glycemic index is an attempt to classify individual foods by the extent to which they raise blood glucose levels. This is an interesting concept, based on the observation that simple carbohydrates from commonly used foods tend to raise blood glucose levels more than do complex carbohydrates from starchy foods (Figure 3). For example, 50 g of carbohydrate from new potatoes has a glycemic index of ‘70, whereas 50 g of carbohydrate from kidney beans provides a glycemic index of approximately 29 [35]. Many factors interact to influence the glycemic response to food. The physical form of food affects the rate of absorption and subsequent rise in glucose levels, as does the rate at which the food is ingested and digested. Foods such as legumes, which are digested less rapidly than other
carbohydrate foods, cause a slower and lower glycemic response. The fiber content of the diet per se does not seem to be the major factor in determining glycemic response, but foods with a high soluble fiber content seem to have a lower glycemic index rating [36]. Because of the complexities in teaching and applying the glycemic index to individual patients, practical application is difficult. However, the concept has stimulated new research into the area of nutritional management of diabetes mellitus that may shape the future of diet therapy.
PRACTICALAPPLICATIONS As new concepts in the science of nutrition for diabetes are clarified, the challenge of putting these concepts into practice remains. Given the general guidelines of a prudent nutrition plan appropriate for the management of diabetes-generous amounts of complex carbohydrate and fiber with restrictions of fat and cholesterol-what can be done to develop a dietary approach that will be suited to individual patients and contribute to the control of diabetes? A critical element in diet effectiveness over the long term is individualization. Flexibility within the guidelines previously outlined should be encouraged to promote adherence. The best nutrition plans are not effective if people do not follow them. Initially, the physician or health care team members should realistically assess the capabilities of diabetic patients and their support systems. The registered dietitian can then develop a specific nutrition plan based on current eating habits, desirable weight estimates, and an education strategy suited to the individual patient. A phased plan for nutrition counseling may begin with the survival phase, shortly after diagnosis, when basics of meal planning are taught. Thereafter, a goal-oriented progression should take place, through phases of increasing information acquisition, incorporation of information into new knowledge and skills, a program of continuing education and reinforcement, and an ultimate goal of promoting positive behavioral change [3’71. The American Diabetes Association/American Dietetic Association Exchange Lists were first released in 1950 and have remained the most acceptable, universal method of meal planning. However, it is unreal-
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istic to suppose that this approach is appropriate for all persons with diabetes mellitus. Alternatives include guidelines such as the United States Dietary Guidelines and Basic Four Food Groups, which provide basic principles of nutrition and diabetes management that can serve a wide spectrum of people because they offer both simplicity and flexibility. HCF Exchanges have been developed to serve as a high-fiber alternatiye to the American Diabetes Association Exchanges [38]. The HCF Nutrition Plan emphasizes foods high in carbohydrate and fiber content and low in fat and cholesterol. To meet these goals, the Exchanges include a Bean group and Starch group.; the traditional Meat exchange group is entitled Proteins to shift the emphasis from meat and highlight other low-fat protein sources such as fish. Counting options, such as Total Available Glucose and the Point System represent other structured meal planning approaches. Menu plans can serve as either the single educational tool for persons of low literacy or as an adjunct to diabetes nutrition guidelines for the self-directed, motivated people [39]. Nutrition instruction and counseling are central to the control of diabetes. Sixty-six percent of patients with diabetes do not possess the requisite knowledge to follow a prescribed diet and do not know what caloric intake has been prescribed [40]. Although adherence to diet plans is notoriously poor, the team approach to education and follow-up can greatly enhance effectiveness.
COMMENTS Diet remains the cornerstone of management for all types of diabetes mellitus. Good glycemic control, desirable serum lipid levels, and the reduction of risk for metabolic, microvascular, and macrovascular complications are the key goals for a diabetes nutrition plan. Recent developments in the rapidly changing field of nutrition have raised questions about the optimal carbohydrate, protein, and fat intake for persons with diabetes mellitus, as well as the use of fiber and the role of the glycemic index. Considerable clinical and experimental data have emerged to support recommendations of a diet generous in complex carbohydrate and fiber and restricted in fat and cholesterol. Current nutrition recommendations for persons with diabetes include all the nutrition principles of a prudent or health-promoting diet. Individual caloric needs should be evaluated to assist the patient in attaining and maintaining desirable body weight. Diets high in complex carbohydrate and fiber improve glycemic control, reduce insulin requirements, and lower serum cholesterol concentrations. Dietary fiber offers distinct health advantages for pertions with diabetes. Because almost all risk factors for atherosclerosis occur more frequently in persons with diabetes mellitus, new emphasis is being placed on limiting fat intake to less than 30 percent of total calories consumed. Alternative sweeteners, whether nutritive or nonnutritive, may be recommended if they are safe and compatible with the nutrition plan. The glycemic index attempts to categoriie foods by the extent to which they raise blood glucose levels. Although this concept may have practical applications in diet planning, further investigation should prove helpful in defining its role.
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The effects of diet components have been extensively studied, and the importance of individualized and flexible nutrition plans to promote adherence should receive further emphasis in future areas of research. Nutrition instruction and counseling are central to the control of diabetes. Persons with diabetes can change their eating patterns and closely adhere to a diet plan if the entire health care ‘team is enthusiastic, supportive, and instructive.
REFERENCES 1. Anderson JW, Gustafson NJ: Nutrition management of hyperlipidemia in diabetes. Pratt Diabetol 1987; 6: 16-20. 2. American Diabetes Association: Nutritional recommendations and principles for individuals with diabetes mellitus: 1986. Diabetes Care 1987; 10: 126-132. 3. Hansen BC: Dietary considerations for obese diabetic subjects. Diabetes Care 1988; 11: 183-188. 4. Henry RR, Wiest-Kent TA, Scheaffer L, eta/: Metabolic consequences of very-low.calorie diet therapy in non.insulin.dependent diabetic and non-diabetic subjects, Diabetes 1986; 35: 155-164. 5. Hollenbeck CB, Coulston AM, Reaven GM: Glycemic effects of carbohydrates: a different perspective. Diabetes Care 1986; 9: 641-647. 6. Wylie-Rosett J: Evaluation of protein in dietary management of diabetes mellitus. Diabetes Care 1988; 11: 143-148. 7. Rosman JB, TerWee PM, Meijer S, et al: Prospective randomized study of early protein restriction in chronic renal failure. Lancet 1984; II: 1291-1296. 6. Nutrition Committee, American Heart Association: Dietary guidelines for healthy American adults. Circulation 1988; T7: 721A-724A. 9. Phillipson BE, Rothrock DW, Connor WE, Harris WS, lllingworth DR: Reduction of plasma lipids, lipoproteins and apoproteins by dietary fish oils in patients with hypertriglyceride mia. N Engl J Med 1985; 312: 1210-1216. 10. von Schacky C, Fischer S, Weber PC: Long-term effects of dietary marine omega3 fatty acids upon plasma and cellular lipids, platelet function and eicosaniod formation in humans. J Clin Invest 1985; 76: 1626-1631. 11. Herold PM, Kinsella JE: Fish oil consumption and decreased risk of cardiovascular disease: a comparison of findings from animal and human feeding trials. Am J Clin Nutr 1986; 43: 566-598. 12. Crouse JR, Grundy SM: Effects of sucrose polyester on cholesterol metabolism in man. Metabolism 1979; 28: 994-1000. 13. The NutraSweet Company: Simplesse product information. January 27, 1988. 14. United States Department of Agriculture, 1986. 15. Craoo PA. Kolterman OG. Olesfskv JM: Effects of oral fructose in normal. diabetic and impaired glucose tolerance subjects-Diabetes Care 1980; 3: 575-582. 16. Crapo PA: Use of alternative sweeteners in diabetic diet. Diabetes Care 1988; 11:
174-182. 17. Food and Drug Administration: Aspartame: commissioner’s final decision, Fed Regist 1981; 46: 38285-38308. 16. Franz MJ: Recent revisions in nutrition guidelines for persons with diabetes, Int Med
1988; 9: 159-168. 19. Lieber CS: To drink (moderately) or not to drink? N Engl J Med 1984; 310: 846-848. 20. Anderson JW: Nutrition management of diabetes mellitus. In: Shils ME, Young VR, eds. Modern nutrition in health and disease. Philadelohia: Lea & Febieer. 1988: 1201-1229. 21. Amatruda JM, Biddle TL, Patton ML, Lockwood DH: Vigorous sbpplemeiiation of a hypocaloric diet prevents cardiac arrhythmias and mineral depletion. Am J Med 1983; 74:
1016-1022. 22. Trowel1 HC: Dietary-fiber hypothesis of the etiology of diabetes mellitus. Diabetes
1975; 24: 762-765. 23. Jenkins DJA, Goff DV, Leeds AR, et al: Unabsorbable carbohydrates and diabetes: decreased post.prandial hyperglycemia. Lancet 1976; II: 172-174. 24. Fuessl H, Adrian TE, BacareseHamilton Al, Bloom SR: Effects of guar on plasma glucose and gut hormone response in type II diabetics. In: Proceedings of the Spring Meeting of the British Diabetes Association, Oxford, 1985; 59. 25. Kiehm TG, Anderson JW, Ward K: Beneficial effects of a high carbohydrate, high fiber diet on hyperglycemic diabetic men. Am J Clin Nutr 1976; 29: 895-899. 26. Story L, Anderson JW, Chen WL, et at Adherence to high-carbohydrate, high-fiber diets: long term studies of non-obese diabetic men. J Am Diet Assoc 1985; 85: 1105-
1110. 27. Anderson JW, Zeigler J, Deakins D: High fiber diets increase insulin sensitivity and carbohydrate disposal in type I diabetic individuals (abstr). Diabetes 1988; 37: 11A. 28. Fukagawa NK, Minaker KL, Hageman G, Young VR, Anderson JW: High.carbohydrate, high fiber’diets increase peripheral insulin sensitivity of healthy young men (abstr). Clin Res
1984; 32: 130. 29. Anderson JW: Nutrition management of metabolic conditions. Lexingron, Kentucky: HCF Diabetes Foundation, 1986. 30. Federation of American Societies for Experimental Biology: Physiological effects and health consequences of dietary fiber. Pilch SM, ed. Bethesda, Maryland: Life Sciences Research Office, 1987.
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SYMPOSIUM 31. Vinik Al, Jenkins DJA: Dietary fiber in the management of diabetes. Diabetes Care 1988; 11: 160-173. 32. Mclvor ME, Cummings CC, Mendeloff Al: Long term ingestion of guar gum IS not toxic in patients with non-insulin dependent diabetes mellitus. Am J Clin Nutr 1985; 41: 891894. 33. Klurfeld DM: The role of dietary fiber in gastrointestinal disease. J Am Diet Assoc 1987; 87: 1172-11777. 34. Anderson JW, Gustafson NJ, Bryant CA, Tietyen-Clark J: Dietary fiber and diabetes: a comprehensive review and practical application. J Am Diet Assoc 1987; 87: 11891197. 35. Jenkins DJA, Taylor RH, Wolever TMS: The diabetic diet, dietary carbohydrate and
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differences in digestibrlity. Diabetologia 1982; 23: 477-484. 36. Franz MJ: Evaluating the glycemic response to carbohydrates. Clin Diab 1986; 6: 129-141. 37. Franz M, Krosnick A, Maschak-Carey BJ, et a/: Goals for diabetes education. Alexandria, Virginia: American Diabetes Association, 1986. 38. Anderson JW: HCF exchanges-the high carbohydrate.high fiber (HCF) nutrition plan. Lexington, Kentucky: HCF Diabetes Foundation, 1987. 39. Green JA: Diabetes nutritional management: a need for meal planning alternatives. The Diabetes Educator 1987; 13: 145-147. 40. American Association of Diabetes Educators: Understanding diabetes mellitus. Continuing Education Self-Study Program, Module 4, 1984.
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